The invention relates to a method for determining a rack force for a steering apparatus of a vehicle, in which the rack force is determined as a function of a steering angle variable which characterizes an actual wheel steering angle or a set point of the wheel steering angle. The invention also relates to a control and/or adjustment device for such a steering apparatus and to a corresponding steering apparatus.
In modern steering apparatuses, for example in an electric power steering (EPS) or a steer-by-wire (SbW) steering system, a target steering torque is determined. A steering torque on a steering means of the steering apparatus, for example on a steering wheel, is adjusted to the target steering torque so as to assist the force applied by the driver when steering the vehicle or to counteract the force applied by the driver. It is known to determine the target steering torque as a function of the rack force.
A method for determining a force acting on a steering gear is known from DE 10 2009 002 706 A1. Since in said method the force is determined directly on the basis of a force acting directly on the steering gear, this may include errors caused by properties of the road that is being traveled. For example, unevennesses, ruts or banking of the road lead to such errors. If the target steering torque is determined on the basis of the force that is subject to errors, in many cases this results in a steering feel that is perceived as uncomfortable by the driver.
The object of the invention is to provide a method for determining a rack force, with which a target steering, force can be generated such that a comfortable steering feel is imparted to the driver and the steering apparatus nevertheless gives the driver feedback that is as realistic as possible regarding the motion state of the vehicle. This object is achieved by a method, a control and/or adjustment device and a steering apparatus.